Since I bought my car it has made a whining from the rear end and just about any speed. You can hear it from outside the car, down the street according to my friend. The sound goes away under throttle I think. I notice some bucking or a kind of "slack" in the drivetrain below 2000 rpm...Im not positive its the drivetrain and not the car running rich and bucking under decel with the haltech. I think its the preload adjustment on the diff. Anyone have any ideas? I pulled the plugs to replace the oil and it looks fine. Oh yeah and its a 4.33 installed by mazda

 

i have the same noise and have posted a few times about it. i never got a good response becides change the diff fluid. i changed the fluid and nothing was any diffrent.

 

yeah, well Im guessing its the preload. Im going to go ahead and order my bearings and Im going to pull it and rebuild it.

 

My FC used to have a whine but only when the clutch was in but I was in gear like taking a turn and shiftin to 2nd but still have the clutch in, a few months later my tranny crapped out and when i swapped trannys I noticed there was absolutely no gear lube in it...
Apparently the previous owner didnt bother to ever check the level of tranny lube... I do that once in a while now...

 

definitely not the tranny. It did it before I swapped to a manual too.

 

The 4.3 needs to be shimmed correctly. The guy that did mine did not shim it out, and it made the whinning noise. There's supposedly a shim kit that you can buy for the install. Make the dealership refund the labor cost - they did not do it correctly.

 

it was done several years ago and about 7,000 miles and I wasnt the owner then.